[NukeNet] Kashiwazaki Kariwa Nuclear Power Plant: updated CNIC analysis

[Citizens' Nuclear Information Center]

I am resending the link along with the full text. (The table doesn't  
come out properly in the article copied below, so I have inserted  
commas to show column breaks.)

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the message.

Philip White

http://cnic.jp/english/newsletter/nit119/nit119articles/ 
kkearthquake.html
  Kashiwazaki-Kariwa Earthquake
Japan's Nuclear Safety Shaken to the Roots

CNIC Report (23 July 2007)

At 10:13 am on July 16 a magnitude 6.8 earthquake struck just off the  
coast of Niigata Prefecture on the Japan Sea side of Honshu, Japan's  
largest island. As a result of the quake, four reactors (units 2, 3, 4  
& 7) at Tokyo Electric Power Company's (TEPCO) Kashiwazaki-Kariwa  
nuclear power plant shut down automatically. At the time, unit 2 was  
being started up after a periodic inspection, while the other three  
units (1, 5 & 6) were still shut down for periodic inspection.

We express our condolences to the families and friends of those who  
lost their lives as a result of the earthquake. So far ten people are  
reported to have died. We are also concerned for the well-being of  
those who survived, some of whom are members of CNIC. Their suffering  
is likely to continue for some time. Perhaps the only fortunate thing  
amidst this misery is that the nuclear reactors shutdown. If they had  
not done so, there could have been a nuclear disaster in which a huge  
amount of radioactive material was released into the environment.

Fire in a transformer
As a result of the quake, a fire occurred in a transformer outside a  
building in unit 3. The transformer was part of the external power  
supply system. It appears that a short in an electric circuit gave rise  
to a spark, which set fire to insulating oil. The ground beneath the  
transformer was raised by 30 cm, while the ground next to the  
transformer, where the electric cables ran, subsided by 15-25 cm. TEPCO  
believes that the relative movement caused a short circuit and that  
this gave rise to the fire.

The fact that it took two hours to put out the fire exposed TEPCO's  
lack of preparedness. However, it turns out that TEPCO is not the only  
power company that is ill prepared to respond to such situations.  
Responses by power companies to a survey by the Mainichi Shimbun  
revealed that although power companies prepare for fires, no special  
consideration has been given to the particular problems of fires which  
occur as a result of earthquakes (Mainichi Shimbun, 20 July 2007). This  
is incredible, given that throughout Japanese history, whenever there  
was an earthquake, fires caused at least as much damage as the  
earthquakes themselves.

Despite the potential seriousness of this fire, TEPCO failed to  
announce whether there was a continual external supply of power and  
whether the emergency generator started up. This is very important  
information, because if the external power supply and diesel generators  
had failed, it would have been impossible to maintain a continual flow  
of coolant to the reactor. Even after automatic shutdown, the fuel in  
the reactor core is still extremely hot. Failure to maintain a  
continual supply of coolant could result in a core meltdown, leading to  
the release of highly radioactive material into the environment. There  
would then be a double disaster: a nuclear disaster on top of an  
earthquake disaster.

Radioactivity released to the environment
Water containing radioactive material was released from unit 6 into the  
sea. TEPCO originally said the quantity of radioactivity involved was  
60,000 becquerels, but it later increased its estimate to 90,000  
becquerels. One would not expect this amount to have any impact on the  
environment or on human health, but TEPCO took far to long to report  
the release. The following account is based on a report published on  
the asahi.com web site on July 21.

At around 12:50 pm, a pool of water was found inside the reactor  
building, but outside the controlled area. Within about an hour and a  
half, workers had analyzed samples and found that they contained  
radioactive material. However, because it was outside the controlled  
area they doubted their results. They collected new samples and  
repeated the analysis twice. It wasn't until about 20:30 pm that TEPCO  
finally reported the release to the authorities. It seems that TEPCO  
employees are still under the spell of the safety myth. They are still  
more inclined to believe the theory rather than the evidence before  
their eyes.

TEPCO also took a long time to work out how the leak occurred.  
Apparently the spent fuel pool overflowed and the liquid leaked out to  
the uncontrolled area through electric power cable tubing. Spent fuel  
pools frequently overflow during earthquakes, so the fact that  
radioactive material was released to sea shows that TEPCO failed to  
adequately address this problem.

On July 17, TEPCO announced that iodine, chromium (Cr-51) and cobalt  
(Co-60) had been released to the atmosphere from the main exhaust stack  
of unit 7. At the time, TEPCO indicated that the release had stopped,  
but it subsequently corrected this, saying that the iodine (I-131,  
I-133) release continued until July 18. TEPCO said that due to a  
failure to manually shut down the turbine grand steam exhaust fan after  
the reactor shut down, iodine and particulates that had accumulated in  
the condenser were sucked out and released through the exhaust stack.  
That is plausible, given that in boiling water reactors (unlike  
pressurized water reactors) the same water that cools the reactor is  
converted into steam to drive the turbines and then condensed in the  
condenser. It is, therefore, to be expected that some radioactive  
material will find its way from the reactor to the condenser.  
Nevertheless, release of these radionuclides automatically raises  
suspicions of damaged fuel assemblies. However, TEPCO stated that,  
given the low level of iodine in reactor water samples and off-gas  
monitor readings, there is no indication that fuel assemblies were  
damaged. TEPCO estimated that the total amount of radioactivity  
released from the main exhaust stack of unit 7 was 4 x 108 becquerels  
(radiation dose of 2 x 10-7 milli-sieverts from iodine and 7 x 10-10  
milli-sieverts from particulate matter).

The earthquake knocked over several hundred drum cans in the storage  
building for low-level solid waste. Of these, around 40 were found  
without their lids on. About 16 liters of liquid leaked, but TEPCO says  
that no radioactivity was found and none was released into the  
environment.

63 problems identified
As of July 21, TEPCO had identified a total of 63 problems. Fifteen of  
these were related to radioactivity. The spent fuel pools of all 7  
units overflowed, although only unit 6 involved a release of  
radioactivity to the environment, and ducts in the exhaust stack of all  
reactors were displaced. There was also some radioactivity found in a  
massive pool of water from damaged pipes in the fire extinguishing  
system of unit 1 (40 cm deep (1,670 m3), fifth floor basement,  
auxiliary building).

Besides these, the following are just a few of the problems that did  
not involve radioactivity. The water level of the spent fuel pools of  
units 1, 2 and 3 dropped then recovered mysteriously. Work platforms in  
the spent fuel pools of units 4 and 7 fell onto the spent fuel storage  
racks. There were oil leaks from several transformers. Some pumps are  
out of order. Blow-out panels in turbine and reactor buildings came  
off. Regular power supply to the administration building was lost and  
the emergency power supply had to be activated.

However, beyond these readily identifiable problems, the question of  
how much the buildings, pipes and equipment were weakened by the  
earthquake remains unanswered. Detailed checks are required, but since  
the impact of the earthquake would not have been uniform, it will not  
be possible to provide complete assurance that the plant is capable of  
withstanding the next earthquake.

Earthquake Resistance Design
Under Japan's old earthquake resistance guidelines, the design basis  
for nuclear power plants (NPP) assumed a "maximum design earthquake"  
(S1) and an "extreme design earthquake" (S2), where S2 was greater than  
S1 (see NIT 112, 103). The "extreme design earthquake" was thought to  
be impossible in reality, but it was taken into account just to be on  
the safe side. However, the earthquake that hit on July 16 exceeded the  
S2 design basis earthquake. Indeed, based on the information released  
by TEPCO, for unit 1 the peak ground acceleration at the plant was 2.5  
times greater than assumed for the S2. The peak ground acceleration in  
the east-west direction was recorded at 680 gal, compared to the design  
basis of 273 gal (see tables). (Only peak ground acceleration data is  
available, because the earthquake exceeded the monitoring system's  
recording capacity.)

Peak Ground Acceleration 16 July 2007 (gal)
Location, North-South,   East-West,  Up-Down
Unit 1,  311,  680, 408
Unit 5, 277, 442, 205
Unit 6, 271, 322, 488

Peak Ground Acceleration S2 (gal)
Location, North-South, East-West, Up-Down (static design)
Unit 1, 274, 273, (235)
Unit 5, 249, 254, (235)
Unit 6, 263, 263, (235)

It is believed that this earthquake was caused by movement of an  
approximately 30 km long and 25 km deep fault. This fault was not taken  
into account during surveys carried out for the design of the  
Kashiwazaki-Kariwa nuclear power plant. Instead, the S2 design basis  
earthquake that was chosen was a magnitude 6.9 quake at an active fault  
20 kilometers away. This was the fault which caused an earthquake in  
the same region in 2004. On that occasion, reactor number 5 shut down  
automatically, but peak ground acceleration did not exceed predictions.

 From analysis of the distribution of the after shocks from the 16 July  
2007 quake, it is now believed that there is an active fault extending  
directly under the Kashiwazaki-Kariwa NPP. Since Japan's earthquake  
resistance guidelines do not permit NPPs to be built directly above  
active faults, Kashiwazaki-Kariwa would not have been chosen to host a  
NPP had this been known at the time. However, it now appears that this  
should have been recognized. After the recent earthquake, Professors  
Takashi Nakata (Hiroshima Institute of Technology) and Yasuhiro Suzuki  
(Nagoya University) analyzed the data in TEPCO's license application  
and concluded that it indicated a fault five times longer than one  
identified by TEPCO (Asahi Shimbun, 20 July 2007). Between 1979 and  
1985, using sonic testing, TEPCO found 4 small faults off the coast of  
Kashiwazaki-Kariwa, but it concluded that they were either not active  
or not important. However, Nakata and Suzuki said that the data  
indicated that three of these small faults were connected and were in  
fact one long 36-kilometer fault and that the fault was probably  
active.

Professor Nakata is the geomorphologist who last year proved that there  
is a previously unidentified active fault near the Shimane nuclear  
power plant (NIT 114). Earthquake studies for Japan's nuclear power  
plants have largely ignored the work of geomorphologists. They are  
taken more seriously now under new earthquake resistance guidelines  
approved in September 2006, but their role is still vague. It seems  
that the nuclear industry does not like them, because they are too good  
at finding active faults.

Clearly Japan's earthquake safety standards are inadequate. This fact  
can no longer be disputed. Given that the size and location of this  
earthquake was not predicted by TEPCO's survey, nor in the government's  
screening process, it is essential that an independent geological  
survey be carried out of the surrounding area, both on land and at sea.  
However, it would appear from the evidence that has already come to  
light that Kashiwasaki-Kariwa is not a safe site for a nuclear power  
plant and that the plant should be shut down permanently.

In just two years, three earthquakes (off the coast of Miyagi  
Prefecture on 16 August 2005, off the Noto Peninsula in Ishikawa  
Prefecture on 25 March 2007, and now this one) have exceeded the S2  
design basis earthquake assumed at the time the plants were built.  
Since the earthquake resistance guidelines were revised, Japan's  
nuclear power companies have been carrying out geological surveys and  
safety checks on the basis of the new guidelines. However, the July 16  
earthquake demonstrates the inadequacy of these measures. For example,  
detailed surveys are only required for a 5 km radius around the plant  
and power companies have until 2012 to complete safety checks. By  
rights, all nuclear power plants should be shut down until these  
surveys and safety checks have been completed. The Nuclear Industrial  
and Safety Agency (NISA) should review its policy of allowing reactors  
to continue to operate while these surveys and checks are carried out.  
However, at a press conference on July 18, NISA's spokesperson, Akira  
Fukushima, repeatedly dodged questions directed at this problem. As  
usual, the government's priority is to keep nuclear power plants  
operating, regardless of safety concerns.

Lessons to be learnt
This was not the biggest earthquake that could possibly hit Japan. This  
one was just a warning. There were enough failures this time to enable  
us to imagine what might happen if a bigger earthquake struck. In  
particular, we saw how the confusion caused by the earthquake led to  
errors and lapses of judgment. We saw equipment failures which in  
themselves might be manageable, but which, when compounded with the  
many other failures that earthquakes inevitably cause, could have been  
catastrophic.

Unfortunately, there is no indication that the government will  
prioritize safety over the narrow economic interests of the power  
companies. The following quote starkly illustrates the obstacles to  
change:

     The official said that during the discussions on new standards in  
2006, it was clear that above a level of about 6.7, "there would be a  
lot of backfitting required" to keep reactors operating. Were Japan in  
the aftermath of this week's quake to make a quake of 7.0 the design  
basis event, he said, for some plants the amount of upgrading needed  
could be economically prohibitive. (Nucleonics Week, Volume 48, Number  
29, July 19, 2007)

Clearly it is important to change the priorities of the central  
government. Mr. Amari Minister of Economy, Trade and Industry ordered  
that the reactors remain shut down until safety has been confirmed. One  
wonders what criteria he might use to determine when they are safe  
again, but it is hard to imagine that his criteria would be based on  
good sense and sound science. Possibly the best hope lies at the local  
level. The mayor of Kashiwazaki City invoked his right under fire  
safety provisions to order that the reactors remain shut down. The  
issue will then come down to the mood of the local population. The  
earthquake shook the people of Kashiwazaki-Kariwa in more ways than  
one. What will it take to convince them that it is safe to operate the  
reactors again?

By Hideyuki Ban (CNIC Co-Director) and Philip White (NIT Editor)

Citizens' Nuclear Information Center
2F-B Akebonobashi Coop, 8-5 Sumiyoshi-cho, Shinjuku-ku,
Tokyo, 162-0065, Japan
Phone: +81-3-3357-3800		Fax: +81-3-3357-3801
Email: cnic at nifty.com		Web: http://cnic.jp/english/